K20a2 on the cheap....

[Deadphishy]

Ok, So my k24 needs to come out because i have really bad piston slap. So this is what i'm doing.
I had some k20a2 pistons cleaned up and had the side skirts recoated. I'm going to do a really light finish hone on the cylinders, replace my k20a3 pistons with the a2's. Put my k20a2 head from the k24 on the a3 block. Including the stage 2 cams. I'll swap Oil pumps over.

I'm looking for just a few bucks have a decent motor that will make some power while i rebuild the k24 and make the required rapairs.

I hope the rods will hold up, but i can't see myself reving the motor past 7500, so it should be ok.


Things i am not doing.

I am not using new rings, I took the Rings off the a3 pistons and they will go back into the cylinder they came from.
I am using a low miles used head gasket.......we will see........
I am not having the motor rebalanced.

I am not looking to get a lot of life out of this motor, so these things should be fine.

[Deadphishy]

Motor is in the car, and running. I've put about 220 miles on it so far in break in. Seems to feel pretty stronge. it's amazing what a little compression does to help you low end grunt.

[mp_02si]

I will post so you dont feel like you are talking to yourself. Not a bad setup for throwing something together that you just have laying around. I thought a2 pistons would not fit a3 rods though???

[Deadphishy]

The pistons will fit a3 rods. The difference is that the k20a3 crank has skinnier rod journals. So k20a2 rods will not fit on a k20a3 crank, as they are to wide. I have k20a2 rods, and i would have used them if they fit on the k20a3 crank. But for the most part all k series pistons will fit any rod.

One thing you can do and it has been done a few times, you can put a k20a2 crankshaft into a k20a3 block. This allows you to use all of the k20a2 internals.

I would have used the stock k20a3 head, if i didn't sell the rockers to someone who was doing a vtec killer set up. the k20a3 cylinder head has a slightly smaller combustion chamber then the a2 head. That means with the stock a2 pistons that i'm using which are 11:1 compression with the stock a2 head, but in an a3 head it would be closer to 11.5~12:1. that added compression coupled with the a3 head would have a lot of pop on the low end. And great MPGs.

[johnkimble]

as long as you aren't over revvving and get a mild tune I don't see any problems with this set up

[Deadphishy]

as long as you aren't over revvving and get a mild tune I don't see any problems with this set up

yes, the much weaker rods will not enjoy being taken over 8k all the time. People are making decent power on stock bottom end k20a3's with Super/Turbo chargers some i'm not worried about the motor that much.

I did use a k20a2 Oil pump on this motor, so oil pressure is not going to be a problem. Specially since the k20a3 block doesn't have Oil squiters.
I did have the side skirts of the used a2 pistons re-coated with a dry film lube. this should really decrease the friction of the pistons, which will decrease some of the stress on the rods.

I am still not use to the power band being so high on the motor. I'm still braking it in, so i'm not beating on the car or taking to high RPMs, But it is so weak around 4-5k compared to the k24. Man i was spoiled with the k24, you didn't have to push that thing at all to get tossed into your seat.

I will say for normal driving however, this motor has plenty of power. and should yeild some pretty impressive MPG numbers. If i can not get over 35mpgs on the highway, i'm going back to stock a2 cams.

[kenscivic]

The only thing that would worry me is the reuse of the head gasket, I always thought once the engine heated up w/ the head gasket it was not reusable. Nice cheap person build though, I like the jew in you.

[mp_02si]

The pistons will fit a3 rods. The difference is that the k20a3 crank has skinnier rod journals. So k20a2 rods will not fit on a k20a3 crank, as they are to wide. I have k20a2 rods, and i would have used them if they fit on the k20a3 crank. But for the most part all k series pistons will fit any rod.

One thing you can do and it has been done a few times, you can put a k20a2 crankshaft into a k20a3 block. This allows you to use all of the k20a2 internals.

I would have used the stock k20a3 head, if i didn't sell the rockers to someone who was doing a vtec killer set up. the k20a3 cylinder head has a slightly smaller combustion chamber then the a2 head. That means with the stock a2 pistons that i'm using which are 11:1 compression with the stock a2 head, but in an a3 head it would be closer to 11.5~12:1. that added compression coupled with the a3 head would have a lot of pop on the low end. And great MPGs.

Ok thats wat it was, I knew it was something like that.

[Deadphishy]

The only thing that would worry me is the reuse of the head gasket, I always thought once the engine heated up w/ the head gasket it was not reusable. Nice cheap person build though, I like the jew in you.

Yes, MLS gaskets have a very thin layer or sealant on them. The sealant however never "cures" so it stays plyable. The problem is the as the metal heats and cools, it expands and contracts, over time that can rub away the sealant. It is a very big risk using an old head gasket. However buying a new one was out of the question. So far the head gasket shows no signs of leaking. Although the Plugs are showing small signs of running lean. Data logs so the map is slightly lean and the ECU is correcting for it.

At the time the honda was down, i was driving my spare car. a 1992 buick century. If anyone knows about the centuries from this time, they know that the have a rust problem. While driving the buick as my daily, my rear right control arm, completely rusted through at the hinge. This ment that the car was then un-repairable, and un-safe to drive. So getting the honda back together was of the most importance.

[kenscivic]

Yes, MLS gaskets have a very thin layer or sealant on them. The sealant however never "cures" so it stays plyable. The problem is the as the metal heats and cools, it expands and contracts, over time that can rub away the sealant. It is a very big risk using an old head gasket. However buying a new one was out of the question. So far the head gasket shows no signs of leaking. Although the Plugs are showing small signs of running lean. Data logs so the map is slightly lean and the ECU is correcting for it.

At the time the honda was down, i was driving my spare car. a 1992 buick century. If anyone knows about the centuries from this time, they know that the have a rust problem. While driving the buick as my daily, my rear right control arm, completely rusted through at the hinge. This ment that the car was then un-repairable, and un-safe to drive. So getting the honda back together was of the most importance.

Ahh i understand. Do you need any parts? I can probably swing some buick parts your way at my cost. OR I got this perfect 89 pathfinder I can sell you.

[Deadphishy]

Ahh i understand. Do you need any parts? I can probably swing some buick parts your way at my cost. OR I got this perfect 89 pathfinder I can sell you.
hahaha, my wife would kill me if i got another car. She hated the buick! which is un-fixable but thank you for the offer. The back end is so rusted i'm surprised is hasn't fallen apart into a million parts.

I think i'm going to fix up the k24. Get it running really stronge, sell this awsome k20a2.5 I honestly see it lasting a good while. Everything was in great shape. I took really good care of the motor while it was in my car.

[kenscivic]

Lol , turn the buick into a lemons racer or dirt track racer.. Weld that shit UPPP

[talonXracer]

None of the MLS that I have used have a sealant on them, they have a coating but it is not for sealing. The sealing is a function of the head bolt/studs clamping force and the crimp edges in the outer layers of the gasket. The reason for not using a MLS gasket a second time is that the crimp edges have been flattened out. Another cause of sealing issues after a rebuild are stretched head bolt/studs that are reused. There are certain items that if reused, will come back to bite you eventually and cost alot more to rectify.

But if you are just needing transpo for a short time, and do not plan on hammering it, you should be good to go untill the K24 has been worked over.

The last time I checked the combustion chambers were almost the same size between the A2 and A3, that shouldnt affect the CR much at all.

[Deadphishy]

None of the MLS that I have used have a sealant on them, they have a coating but it is not for sealing. The sealing is a function of the head bolt/studs clamping force and the crimp edges in the outer layers of the gasket. The reason for not using a MLS gasket a second time is that the crimp edges have been flattened out. Another cause of sealing issues after a rebuild are stretched head bolt/studs that are reused. There are certain items that if reused, will come back to bite you eventually and cost alot more to rectify.

But if you are just needing transpo for a short time, and do not plan on hammering it, you should be good to go untill the K24 has been worked over.

The last time I checked the combustion chambers were almost the same size between the A2 and A3, that shouldnt affect the CR much at all.

According to some piston manufacturers they are different. they give two different compression ratios for the pistons depending on the head. Looking on them side by side, the Front and rear edges of the A3 seems to be flatter and less sloped then the a2. They were pretty close, but I think i convinced myself they were different.

[Deadphishy]

"Cometic Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket."

[talonXracer]

The rubber coating is not intended to seal the combustion chambers, that again is entirely a function of the crimp and clamping forces, Cometic adds the rubber for a single reason, it will HELP seal the coolant areas when they have not been properly machined(decked) to remove the imprint the previous gasket created in the aluminum, reusing the Cometics will be an even larger issue than reusing a stockie from our experience.

[Deadphishy]

Well in my book, if it stops something from leaking, It's a sealant. So Yes as stated before MLS gaskets for k20a's have a thin sealant on them. I don't remember saying anything about said sealant being able to seal a combustion chamber?